Arrangement for connecting a rod end to a headed pin and method of manufacture

ABSTRACT

An arrangement and method of manufacture for providing a connection between one end of a control rod and a headed pin includes a hard plastic housing having a pin receiving cavity defined therein, the housing overmolded over the rod end and a soft elastomeric vibration isolator to hold the same together without assembly clearances or subjecting the vibration isolator to direct pressure from the pin to avoid excessive lash in the connection. Retention prongs are integrally molded and configured to engage the head of the pin when inserted in the cavity to be deflected to allow assembly and thereafter resist extraction, with the insertion forces much lower than the extraction force.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. provisional applicationsSer. No. 60/386,986, filed Jun. 7, 2002 and Ser. No. 60/400,082, filedJul. 31, 2002.

BACKGROUND OF THE INVENTION

This invention concerns rod end terminal connections commonly used toconnect control rods to pins mounted to automobile transmission leversand the like to enable shifting of the transmission by the driver of theautomobile. The pin is retained in a housing by a ball feature head onthe pin snap fit to retention features on the housing. It has becomestandard practice to interpose a vibration isolator between theconnected rod and pin to prevent vibrations from being felt by thedriver when grasping a shifter or other member. See U.S. Pat. No.4,581,953 for an example of such a connection.

The vibration isolator is usually constructed of a soft compressiblematerial and excessive lash can result if the isolator material isdirectly contacted by the pin.

Such connections have been provided by assembling several partstogether, and the necessary clearances for assembly also contribute toexcessive lash at the connection.

The cost of manufacturing such linkages typically is high due to theneed to assemble several components, and the need to insure that properassembly of the components has been accomplished.

Another difficulty is encountered in designing the usually snap fitassembled pin and rod connection so that the force to assemble theconnection must be low while the force resisting disconnection of thecomponents must be much higher.

It is the object of the present invention to provide an arrangement forproviding a connection between a pin and control rod including avibration isolator which minimizes lash between the connectedcomponents.

It is a further object to provide such an arrangement which can bemanufactured at low cost.

It is yet another object to provide a snap fit pin-rod connection inwhich a desired greater separation force and lesser assembly force canbe easily designed for.

SUMMARY OF THE INVENTION

These and other objects which will become apparent upon a reading of thefollowing specification and claims are achieved by an arrangement forestablishing a rod end terminal connection having a vibration isolatorof minimal thickness interposed between the rod and an overmoldedminimally compressible hard plastic housing capturing the rod end and avibration isolator interposed between the rod end and a pin receivingcavity defined by a hard plastic structure enclosed within the housing.Preferably the vibration isolator is itself overmolded onto the rod end,received in grooves in the rod and to be securely locked thereto. Thehard plastic defined cavity is configured to receive the pin and aplurality of integral arcuate prongs are arranged about the inside ofthe cavity. The prongs are readily deflectable outwardly engagement ofthe head of the pin with sloping prong surfaces to accommodate insertionof the pin, but pin movement out is resisted by flat prong ends whichrequires application of a desired high extraction force to deflect theprongs and allow removal of the pin.

The overmolding of the hard plastic housing eliminates assembly ofseparate parts as well as eliminating clearances and lash resulting fromhaving separate parts. The housing opening has an overlying web blockingentrance of the pin into the cavity from the wrong side to insureinsertion of the pin into the housing from the prior side.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an arrangement for establishing rod endhead pin connection according to the invention.

FIG. 2 is a plan view of the arrangement shown in FIG. 1 with afragmentary view of a rod end.

FIG. 3 is a vertical sectional view taken through the rod end terminalconnection shown in FIG. 1.

FIG. 4 is a horizontal sectional view taken through the rod end terminalconnection shown in FIG. 1.

FIG. 5 is a fragmentary partially sectional perspective view from oneside of the connection and mated pin shown in FIGS. 1-4.

FIG. 6 is a fragmentary partially sectional endwise perspective view ofthe connection shown in FIGS. 1-5.

FIG. 7 is a fragmentary plan view of a connection with a mating pinaccording to a second embodiment of the invention.

FIG. 8 is a view of a vertical section through the connection shown inFIG. 1.

FIG. 9 is a plan view of an assembled inner core piece and vibrationisolator components included in the connection shown in FIGS. 7 and 8.

FIG. 10 is a side elevational view of the assembled inner piece core andvibration isolator components shown in FIG. 9.

FIG. 11 is a perspective view of the inner core and assembled isolatorcomponents shown in FIGS. 9 and 10.

FIG. 12 is a perspective fragmentary view of the rod and terminalconnection and mating pin shown in FIGS. 7 and 8.

DETAILED DESCRIPTION

In the following detailed description, certain specific terminology willbe employed for the sake of clarity and a particular embodimentdescribed in accordance with the requirements of 35 USC 112, but it isto be understood that the same is not intended to be limiting and shouldnot be so construed inasmuch as the invention is capable of taking manyforms and variations within the scope of the appended claims.

Referring to the drawings, and particularly FIGS. 1-6, the presentinvention provides an arrangement for establishing a connection betweena headed pin 10 and one end of a steel control rod 12. Such connectionsare commonly used to couple a transmission control rod to an automotivetransmission lever by a pin allowing relative rotation. Other controllinkage systems for automotive and other applications widely use suchconnections which allow a changing angle of the control rod on the pinas it is advanced retracted.

This connection includes a thin walled (approximately 1 mm thick) softelastomeric vibration isolator 14 preferably molded in place onto theone end of the control rod 12, with a recess 16 on the one end of therod 12 keying the vibration isolator 14 to insure retention thereon. Therecess 16 also forms an annular feature 17 in the vibration isolator.The vibration isolator 14 could also be separate molded and assembledonto the one end of the control rod 12 (a suitable material is BayerDesmopan 453 polyester polyethylene based grade) Shore hardness scale53D (ASTM D2240).

A pin receiver housing 18 is molded over the vibration isolator 14 andprojects in a lengthwise direction away from the one end of the rod 12to offset a hard plastic structure defining a pin receiving cavity 20extending in a normal direction from the longitudinal axis of thecontrol rod 12.

A portion of the housing 18 is received into the annular recess 17formed in the vibration isolator 14 to be positively keyed thereto forsecure retention.

The housing 18 is molded from a hard plastic such as Dow Vydyne R533(Nylon 66% graphite filled (33%), Rockwell harness scale M95 (ASTMD785).

A pair of pin retention features comprising arcuate prongs 22 areintegrally formed on opposite sides of the cavity 20. Each prong 22includes an axially extending base wall 24 spaced inwardly from theinside of the housing 18 to create a space allowing a radially outwarddeflection thereof.

A radially inward projecting lip portion 26 extends from the free end ofthe base wall 24, having a sloping undersurface 28 and a flat endsurface 30 at the top as viewed in the drawings.

The lower end of the cavity 20 is open while a web 32 extends thereacross at the top to provide an orientation feature insuring correctassembly with the pin 10 able to be inserted only from below as seen inthe drawings.

The pin 10 has a spherical head 34 which when inserted into the cavity20 deflects the prongs 22 radially outward facilitated by the slopingundersurface 28 of the prongs being cammed outwardly by the sphericallycurving head 34. Integral ribs 23 limit outward deflection of the prongs22.

After the head 34 is inserted sufficiently, the head 34 passes lips 26of the prongs 22 allowing the prongs 22 to snap back to present the flatend face to the undersurface of the head 34.

A flange 38 on the pin 10 limits further insertion travel of the pin 34by engaging the bottom 40 of the housing 18.

The insertion force required to install the pin 10 is much less than theforce necessary to remove the pin 10 as a result of the slopingundersurface 28 and the flat end face 30. By varying the thickness ofthe wall 24, any particular insertion force maximum and extraction forceminimum can be designed for to meet the application requirements. Thewall 24 is placed in bending by the camming out of the prongs 22 as theball head 34 is inserted.

The manufacturing process involves molding the vibration isolator 14 tothe one end of the rod 12.

The manufacturing steps are as follows:

This subassembly is then placed in a mold and housing 18 is overmoldedaround the isolator-rod subassembly, the housing 18 having a portionlocated at one end of the rod 12 and formed with a socket opening withradially inwardly projecting engagement prongs for securing the pin. Thehousing 18 in being molded from a hard plastic material, a lowinstallation force for installing the pin can be achieved compared withmuch higher extraction forces required to separate the housing 18 fromthe pin 10.

The specific manufacturing process steps are as follows:

The vibration isolator 14 is installed around the end of the steel rod12. The groove 16 in the end of the rod 12 will match up to an innerridge on the isolator. The vibration isolator 14 is molded around theend of the steel rod 12 with the groove and ridge matching.

Once the vibration isolator 14 rod 12 subassembly is made, molding ofthe final terminal assembly takes place. The vibration isolator 14 rod12 subassembly is placed in the mold into a predetermined position. Nospecial position for orientation is needed. The prongs 22 and loadfeature of the housing 18 is then molded to create the final assembly.This molding process interlocks the vibration isolator 14 rod 12subassembly with the newly molded housing 18.

This connection and method provides several advantages. The first isthat the hard plastic housing 18 with engagement prongs 22 comprise asocket contacting the pin 10, allowing the design of the prongs 22 toset the amount of installation and extraction force desired. By changingthe prong design, i.e., the thickness of the wall, the amount ofinstallation load required to secure the pin 10 can be reduced to meetany requirements and still maintain the required minimum extractionforce.

The second advantage is that by molding the housing 18 around thevibration isolator 14 and steel rod end, this will provide increasedstrength to the rod end assembly and ensure that the housing 18,vibration isolator 14, and steel rod 12 are securely assembled. Thisdesign will also interlock these components to eliminate any tolerancegaps between individual parts. Prior designs had the possibility fortolerance gaps between parts, which will cause free play in the systemknown as “lash”.

The third advantage is that the vibration isolator 14 is wrapped aroundthe steel rod 12 to avoid direct contact with the pin 10. The vibrationisolator 14 is molded with a small cross section wall to lower thethickness of material subject to compression. This will lower systemlash and while still maintaining adequate vibration dampeningcapabilities.

The fourth advantage is a reduction in manufacturing cost. By moldingthe housing 18 over the vibration isolator/steel rod subassembly thereis a reduction in cost for manufacturing the connection.

The fifth advantage is obtained by the addition of the orientationfeature 36 to the housing 18. By adding this feature integrally thehousing 18 can only go onto the pin 10 in one direction. Previously thiswas done by installing a separate component, increasing the cost ofmanufacture.

This design will make it easier to install on the vehicle, reduces cost,and reduces the number of parts in the assembly.

The second embodiment is shown in FIGS. 7-12, in which a hard plastichousing 38 is directly molded to one end of the control rod 12.

The ring shaped vibration isolator 40 is assembled onto a generallycylindrical hard plastic core piece 42 separately molded. The housing 38is molded over the vibration isolator 40. Thus, the vibration isolator40 does not directly contact the pin 10.

The core piece 42 has a central pin receiving cavity 46 formed withinwardly facing deflectable prongs 44 and orientation feature 48 as inthe first described embodiment.

A ridge 43 on the core piece 42 forms grooves 45 matching grooves 47 onthe vibration isolator 40 on the core piece 42 and, together with aridge 41 on the vibration isolator 40, these ensure mutual retention tothe overmolded housing 38.

The vibration isolator 40 is installed around the inner core piece 42.The grooves 45 match up on both parts. The vibration isolator 42 isfully assembled around the inner core piece 42 and the grooves matched.Direction does not matter since the vibration isolator 42 is symmetricaland will go on either direction.

The inner core piece subassembly is placed in the mold along with thegroove end of the steel rod 12. The inner core piece subassembly isinstalled on a special pin in the mold. This special pin correctlypositions the inner core piece subassembly so that the load path featureof the inner core piece 42 is in an axial line with the steel rod 12.This will insure that the contact prongs 44 will be positioned 90degrees to the steel rod 12.

Once the inner core piece subassembly is in place, the steel rod 12 isplaced in the mold. The rod 12 is positioned so that the rod endcontacts the ridge 43 vibration isolator 40. This will serve as aposition stop for the steel rod 12. This stop feature will make iteasier for the operator to properly place the steel rod 12 for the finalmolding.

Once the steel rod 12 and the inner core piece subassembly are correctlyin place, the outer housing 38 is molded over these two othercomponents. This molding process interlocks the inner core piecesubassembly and the steel rod to form the final terminal rod assembly.

1. An arrangement for connecting a one end of a control rod to a headedpin to enable driving of said pin by motion of said control rod, incombination with said control rod and said headed pin, comprising: ahousing made of a hard plastic and defining a pin receiving cavity, withone or more retention features projecting into said cavity and engagingsaid headed pin when inserted therein so as to be retained therein; avibration isolator made of an elastic material softer than said housing,said vibration isolator fit over said one end of said control rod; andsaid housing overmolded onto said vibration isolator join together saidhousing, said one end of said rod, and said vibration isolator. 2.(canceled)
 3. (canceled)
 4. (canceled)
 5. The arrangement according toclaim 1 wherein said one end of said rod has a groove formed therein,and said vibration isolator is fit into said groove, and said housingovermolded onto an annular feature formed on the exterior of saidvibration isolator.
 6. The arrangement according to claim 5 wherein saidvibration isolator has a wall thickness on the order of one millimeter.7. (canceled)
 8. (canceled)
 9. (canceled)
 10. The arrangement accordingto claim 1 wherein said one or more retention features comprise one ormore prongs projecting into said cavity and having radially deflectableportions able to be deflected by a headed portion on said pin and allowpassage into said cavity, said head of said pin after passage into saidcavity.
 11. The arrangement according to claim 10 wherein said prongsare each formed with an axially extending base wall radially spaced froma core structure portion and also having a lip, projecting inwardly fromsaid wall, and having a sloping under surface to be engaged by said headon said pin to cause said radial deflection of said associated prong,and a flat surface engaging said head after said pin head has beeninserted past said prongs to retain said pin in said cavity.
 12. Thearrangement according to claim 1 further including a web integrallymolded into said housing extending over said cavity on one side toprevent insertion of said pin from said one side.
 13. A method ofconstructing a driving connection between one end of a control rod and aheaded pin, comprising the steps of: molding a hard plastic housing toextend over said one end of said control rod; forming a cavity in ourwithin said housing offset from said one end of said rod and configuredto receive said headed pin; forming at least one feature within saidcavity engaging said headed pin upon insertion therein to retain thesame; interposing an elastomeric vibration isolator softer than saidhard plastic housing between said hard plastic housing defining saidcavity and said one end of said rod and overmolding said housing ontosaid vibration isolator when molding said housing to thereby jointogether said housing, said one end of said rod and said vibrationisolator.
 14. The method according to claim 13 wherein said step offorming said cavity is included in the step of molding said housing. 15.The method according to claim 14 further including the steps of locatingsaid vibration isolator on said one end of said rod and overmolding saidhousing over said vibration isolator on said rod.
 16. The methodaccording to claim 15 further including the step of molding saidvibration isolator as a tubular structure disposed over said one end ofsaid rod prior to overmolding said housing onto said vibration isolator.17. (canceled)
 18. The method according to claim 16 wherein in said stepof molding said vibration isolator to said one end of said rod, saidvibration isolator is formed with a thin wall on the order of onemillimeter in thickness.
 19. The method according to claim 13 whereinsaid step of forming at least one retention feature comprises the stepof molding a plurality of integral prongs in said hard plastic housingextending radially inward into said cavity configured to engage a headportion of said pin and be deflected radially outward thereby to allowpassage of said head portion and to thereafter engage said head portionto retain the same in said cavity.
 20. The method according to claim 19wherein said prong molding step includes forming a sloping under surfaceon said prongs to aid in producing radial outward deflection by passageof said pin head portion, and a flat surface on the end thereof engagingsaid pin head portion to resist extraction whereby a much greater forceis required for extraction than for insertion of said pin.